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Optical Fiber Technology 11 (2005) 131–145

www.elsevier.com/locate/yoft

Characterization of optical fibers for optimizationof a Brillouin scattering based fiber optic senso

Kellie Brown∗, Anthony W. Brown, Bruce G. Colpitts

Department of Electrical Engineering, University of New Brunswick, Fredericton, NB E3B 5A3, Canada

Received 16 March 2004

Available online 2 October 2004

Abstract

Brillouin scattering-based distributed fiber optic sensors are powerful diagnostic and montools for structural health. Much research has been focused on improving the spatial, stratemperature resolutions of these systems, mainly by the use of signal processing and improvement. In contrast, there has been little published work on optimizing the sensor fiber itself. A nof optical fibers have been measured in order to determine how to optimize their Brillouin cteristics including the number of Brillouin peaks, the frequency of the peaks, their linewidthtemperature and strain coefficient of each peak, and the Brillouin temperature- and strain-lincoefficients. Among other results, it is shown that raising the intrinsic Brillouin frequency of theincreases the strain and temperature coefficients of the fiber for the main Brillouin peak, whinot been previously reported. 2004 Elsevier Inc. All rights reserved.

Keywords: Brillouin scattering; Distributed sensor; Temperature coefficient; Strain coefficient; Linewidth

1. Introduction

Brillouin scattering based distributed fiber optic sensor systems are powerful diagand monitoring tools for many applications [1,2]. They can measure strain and/or teature in a distributed manner and may be tens of kilometers long [3,4]. Much res

* Corresponding author. Fax: 1-506-453-3589.E-mail address: [email protected] (K. Brown).

1068-5200/$ – see front matter 2004 Elsevier Inc. All rights reserved.doi:10.1016/j.yofte.2004.08.004

132 K. Brown et al. / Optical Fiber Technology 11 (2005) 131–145

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has been focused on improving the spatial, strain, and temperature resolutions osystems, mainly by the use of signal processing and improved instrumentation [5contrast, there has been little recent published work on optimizing the sensor fiberA few research groups have been working on designing optical fibers in order to tailoBrillouin scattering characteristics for various applications, such as controlling the slated Brillouin scattering (SBS) threshold [7]. Others have recorded the Brillouin spof various optical fibers but not given their temperature and strain dependent charatics [8,9]. We provide a much more detailed look at the Brillouin scattering charactertowards optimizing the optical fiber itself for distributed sensor systems. Ten differentical fibers have been characterized in order to compare and contrast the sensitivitievarious fibers to temperature and strain.

2. Brillouin scattering based fiber optic sensors

Brillouin scattering is a three-wave interaction between an incident photon, an acphonon, and a backscattered photon. The phonon causes periodic areas of diffefractive indices of the glass which basically act as a moving Bragg grating, scing light backwards. Phonons in the optical fiber cause the light to be backscattethe Bragg condition is met. Because the phonon is moving, the backscattered lDoppler frequency shifted. The frequency shiftvB is called the Brillouin shift and is giveby [10]

vB = 2nva

λi, (1)

wheren is the effective refractive index of the fibre,λi is the wavelength of the incidenlight, andva is the acoustic velocity of the phonon. For standard single mode fibre (Sthe Brillouin frequency shift is about 12.8 GHz at 1310 nm.

The amount of frequency shift depends on the strain and temperature conditionsfibre. Strain and temperature cause then and va of the fibre to change. It is this straand temperature-dependent shift which allows Brillouin scattering to be used as aing mechanism. The Brillouin frequency is linearly related to the strain and tempeconditions of the fibre [11,12] by

νB(T ) = CT T + νB0, (2)

νB(ε) = Cεε + νB0, (3)

whereCT is the temperature coefficient in MHz/◦C, T is the temperature in◦C, νB0 is thereference Brillouin frequency,Cε is the strain coefficient in MHz/µε, andε is the strain.Typical values ofCT andCε for SMF at 1319 nm are 1.2 MHz/◦C and 0.058 MHz/µε,respectively. Since bothε andT cause a change invB, it is difficult to separate their effects

Brillouin scattering in an optical fibre is frequency dependent. The Brillouin gain strum is generally Lorentzian in shape and is centred aboutνB [10]:

g(v) = gB2, gB = 4πn7p2

2, (4)

1+ 4((v − vB)/�vB) 3cλ ρνa�νB

K. Brown et al. / Optical Fiber Technology 11 (2005) 131–145 133

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aveGeO

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wheregB is the Brillouin gain,p is the longitudinal photoelastic coefficient,ρ is the ma-terial density,λ is the pump wavelength, and�νB is the linewidth. The Brillouin gainbandwidth or linewidth is typically about 50 MHz (FWHM) at 1319 nm. The measuBrillouin linewidth depends on the pulse width, the strain and temperature of the fibeand fiber composition [14]. The Brillouin linewidth, as well as peak power, has beento aid in separating the effects of temperature and strain on the Brillouin frequencthough the resulting published strain and temperature accuracies are not sufficient fpractical applications [13,15].

Some optical fibers exhibit multiple-peaked Brillouin spectra. This is due to the eof dopants and geometrical parameters such as core size [8]. The presence of mpeaks has led some researchers to use these to separate the effects of strain and temon the Brillouin frequency [16,17], and thus measure both strain and temperatureencouraging results.

3. Sensor system and fibers

The sensor system used for the fiber characterization is based on the copropagating pump and probe method, which has been described elsewhere [5].time domain reflectometry is used to obtain spatial information. Two (approximateand 90 m long) SMF28 lead fibers were used to connect the two ends of the sensorto the fiber under test. Brillouin spectra were obtained for the input wavelength of 131The input laser power levels were not changed over the measurement campaign. Easample was about 15 m in length. All fibers were calibrated for their temperature, sand linewidth coefficients using a temperature controlled box and a translation stagapplying known strains). To calibrate a fiber for temperature, the fiber was subjecknown varying temperatures from 0 to 30◦C and its Brillouin frequency recorded. Thslope of the Brillouin frequency shift vs temperature graph is the Brillouin temperaturefficient,CT . The strain coefficientCε was obtained in a similar manner. A pulse width40 ns was used for the temperature calibrations. This width was chosen since shortewidths causes linewidth broadening which obscures some of the multiple peak strfor some fibers. Shorter pulse widths (16 ns) were used for strain measurements tspectral distortion since the strained section of the fiber sample fiber was only 2.5length.

Table 1 shows the mode field diameter (MFD), the outer (buffer) coating diametevarious notes for the optical fibers characterized in these measurements. With the exof the INO 18 mol% GeO2 doped, and Corning SMF 28 fibers, all fibers were manufactby OFS. Yeniay et al. [8] show the refractive index profiles of the AllWave and TrueWfibers as being rounded step index and parabolic-like, respectively. The SMF28 and2

doped are step index profiles. The fibers were encased in 245, 250, and 900 µm bunoted in Table 1. The cut-off wavelength for all fibers is 1260 nm with the exception oUltraWave fibers. Their cutoff is 1530 nm, which means that they operate in the multiregion for this sensor system.


ive

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Table 1Characteristics of optical fibers tested

Fiber MFD MFD Buffer Notes1310 nm (m) 1550 nm (m) diameter (m)

Corning SMF28 9.2 10.4 900AllWave 9.2 10.5 900 No OH− attenuation peakDepressed Cladding 8.8 9.7 900 2 cladding layersClearLite 1310 6.7 7.5 245 Small MFDTruePhase 1310 9.3 245 Polarization maintainingUltraWave IDF 6.2 245 Negative dispersion slope negat

dispersionUltraWave SLA 11.9 245 Large effective area non dispersi

shiftedTrueWave RS 8.4 245 Low dispersion slope parabol

core index profile [8] multiple cladding layers

TrueWave XL 9.5 245 Large effective area negative dpersion

INO GeO2 doped 250 18 mol% GeO2 doped core 3.6 µmcore diameter

Fig. 1. Brillouin spectra for (A) AllWave, (B) ClearLite, (C) UltraWave IDF, (D) TrueWave RS, and (E) TrueWXL.

4. Spectra

The spectra of all fibers recorded in Table 1 were obtained. SMF 28, DeprCladding, TruePhase, UltraWave SLA, and the INO doped fiber all exhibited single pAllWave, ClearLite, UltraWave IDF, and TrueWave RS all have double-peaked spand the TrueWave XL has a triple-peak spectrum, as shown in Fig. 1. The spectrain the figure have all been normalized. Yeniay et al. [8] observed triple peaked spec


3,

ents.Thereandationystem

theire INOnextBril-used

Table 2Brillouin frequency shift and linewidth for each fiber at room temperature and zero strain

Fiber Peak 1, Peak 1, Peak 2, Peak 2, Peak 3, PeakBrillouinfrequency

Linewidth(MHz)

Brillouinfrequency

Linewidth(MHz)

Brillouinfrequency

Linewidth(MHz)

(MHz) (MHz) (MHz)

Corning SMF28 12,790 47AllWave 12,737 53 12,799 60Depressed Cladding 12,804 44ClearLite 1310 12,539 43 12,598 55TruePhase 1310 12,825 44UltraWave IDF 12,295 70 12,503 66UltraWave SLA 12,848 72TrueWave RS 12,537 57TrueWave XL 12,463 45 12,681 42 12,884 50INO GeO2 doped 12,046 56

Fig. 2. Brillouin frequency vs MFD for different fibers.

AllWave at 1550 nm, however, a third peak was not visible in our 1319 nm experimThe reason for this is unknown, however, AllWave has a rounded step index profile.is likely a difference in the power distribution in the fiber at the wavelengths of 13191550 nm, which would cause different Brillouin spectra for each case. As well, attenuat 1319 nm is about twice that at 1550 nm; perhaps the signal-to-noise ratio in our sis inferior to the system described in [8], obscuring the low level third peak.

The Brillouin frequency shifts for each of these are recorded in Table 2, as well aslinewidths for 40 ns pulse widths, measured at zero strain and room temperature. Thdoped fiber had the lowest Brillouin frequency, at 12,046 MHz. Of the OFS fibers, thelowest was the UltraWave IDF at 12,295 MHz. Figure 2 shows a plot of the measuredlouin frequency vs the mode field diameter at 1550 nm for each fiber (1550 nm was


cient

for theases,ts byasingt eitherradiuslso beradii,een pre-4,20].

strain

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Table 3Temperature coefficient with standard error for all fibers

Fiber Peak 1, Peak 2, Peak 3,temperature coefficient temperature coefficient temperature coeffi(MHz/◦C) (MHz/◦C) (MHz/◦C)

Corning SMF28 1.69± 0.09AllWave 2.26± 0.01 2.59± 0.08Depressed Cladding 2.84± 0.10ClearLite 1310 1.55± 0.01 1.17± 0.28TruePhase 1310 1.61± 0.08a

UltraWave IDF 1.48± 0.02 2.16± 0.37UltraWave SLA 1.71± 0.04TrueWave RS 1.54± 0.01 1.77± 0.09TrueWave XL 1.52± 0.03 1. 44± 0.09 1.59± 0.07INO GeO2 doped 1.38± 0.04

a This calibration curve actually fitted better to a quadratic function, although linear curvefit was used.

because some of the MFDs were not known at 1319 nm, and the MFD was unknownINO fiber). It is shown that as the MFD (and correspondingly the core radius) increso does the Brillouin frequency. This is in opposition to previously published resulShiraki et al. [18] which showed that the Brillouin frequency decreases with increcore radius. However, it has been shown by simulation and measurement [19] thascenario can be true, and whether the Brillouin frequency raises or lowers with coredepends on the dopants (acoustic velocities) and geometry of the fiber. It should anoted that the results of Shiraki et al. [18] were for identical fibers with changing corewhereas the fibers tested here may have different dopants and geometries. It has bviously reported that increasing the dopant level decreases the Brillouin frequency [1

5. Temperature and strain coefficients

As mentioned previously, each fiber was calibrated to obtain their temperature andcoefficients. In this paper, the temperature coefficient is given with units of MHz/◦C andthe strain coefficient with units of MHz/µε. If one wants to design a Brillouin sensfor measuring only strain, it would be ideal to have a large strain coefficient in contion with a small temperature coefficient. Conversely, if one wanted to design a Brilsensor to measure only temperature, a small strain coefficient and a large temperaefficient would be ideal. Table 3 gives the measured temperature coefficients for alland Table 4 gives the measured strain coefficients. The standard error shown was gthe curvefitter (which uses the Marquardt–Levenberg algorithm) when the regresseach data set was performed. The coefficients for peaks 2 and 3 generally have largdard errors because these peaks have much less power than the main peaks, as obFig. 1.

The AllWave, Depressed Cladding, and SMF 28 fibers have relatively large temture coefficients because of their 900 µm buffer coating, an effect previously observKurashima et al. [12]. For these fibers, the large cross-sectional area of the buffer r


nt

ermals, thees notng the

fiber

ent vserseters.

Table 4Strain coefficient with standard error for all fibers

Fiber Peak 1, Peak 2, Peak 3,strain coefficient strain coefficient strain coefficie(MHz/◦C) (MHz/◦C) (MHz/◦C)

Coming SMF28 0.0558± 0.0003

AllWave 0.0566± 0.0001 0.567± 0.0002Depressed Cladding 0.0566± 0.0007ClearLite 1310 0.0545± 0.0004 n/aa

TruePhase 1310 0.0588± 0.0003UltraWave IDF 0.0527± 0.0002 0.0517± 0.0007UltraWave SLA 0.0585± 0.0003True Wave RS 0.0563± 0.0005 0.0543± 0.0008TrueWave XL 0.0548± 0.0002 0.0550± 0.0019 0.0554± 0.0003INO GeO2 doped 0.0547± 0.0002

a Shorter pulse width required obscures this peak.

Fig. 3. Temperature coefficient vs Brillouin frequency for all 245 µm buffer fibers-main peak.

to that of the fiber itself causes the temperature effect to be dominated by the thexpansion of the buffer rather than that of the glass. Of the 245 µm buffer fiberUltraWave SLA was the most temperature sensitive. Since the buffer coating dohave a significant effect on the strain coefficient, for AllWave and Depressed Claddistrain coefficient is quite ordinary when compared to the others. The UltraWave IDFhas relatively small strain coefficients of 0.0527 and 0.0517 MHz/µε. The polarization-maintaining TruePhase had the largest strain coefficient of 0.0588 MHz/µε.

Figure 3 reveals a rather interesting result. It is a plot of the temperature coefficithe fiber Brillouin frequency for each fiber’s main Brillouin peaks (900 µm buffer fibnot included). It reveals approximately a linear relationship between these two param


one toensitiveem-urately

have[19].gain

in shift

2 ofe main6 aregain,s thatfiber

cientcientsign ausing

dif-ppliedmeter

Fig. 4. Temperature coefficient vs Brillouin frequency for all 245 µm buffer fibers-second peak.

This result has not been previously reported in the literature. Studying Fig. 4 leadsthe conclusion that one can design an optical fiber to be more or less temperature sby raising or lowering the fiber’s intrinsic Brillouin frequency. Increasing the fiber’s tperature coefficient improves the accuracy of the sensor system; it is easier to accmeasure large frequency shifts than small ones.

The tailoring of the Brillouin frequency for optical fibers has been done; Yu et al.been able to tailor the Brillouin shift by changing the fiber geometry and doping levelsKoyamada et al. recently reported their work on designing and simulating Brillouinspectra [21]. SBS suppressing fibers have also been developed where the Brillouhas been tailored [18].

Figure 4 is a plot of the temperature coefficient vs the Brillouin frequency for peakthe fibers. It shows that peak 2 of each fiber shows the opposite trend to that of thpeak; the temperature coefficient is lowered with Brillouin frequency. Figures 5 andplots of the measured strain coefficient vs Brillouin frequency for peaks 1 and 2. Athey show an approximately linear (previously unreported) relationship which meanone should be able to make the fiber more or less strain sensitive by tailoring theBrillouin frequency. It is interesting to note that the slope of the temperature coeffiplot of Fig. 3 is positive and negative for the one of Fig. 4, whereas the strain coeffiplots for both peaks show a positive slope. This behavior may make it possible to defiber which is less temperature sensitive and more strain sensitive, or vice-versa, bythe peak 2 temperature coefficients.

6. Brillouin linewidth coefficients

Some Brillouin sensor systems make use of the Brillouin linewidth in order to helpferentiate between the effects of strain and temperature on the Brillouin frequency. Astrain and temperature do affect the Brillouin linewidth, however, the use of this para


canz to asfromsed byment er-ivably

ture-h vs

Fig. 5. Strain coefficient vs Brillouin frequency for main peak of OFS fibers and SMF28.

Fig. 6. Strain coefficient vs Brillouin frequency for second peak of OFS fibers.

has limitations. The Brillouin linewidth changes with the pulse width used [22], andchange quite remarkably at pulse widths between 1 and 20 ns, from about 50 MHmuch as 150 MHz FWHM [23,24]. A slight unaccounted-for change in pulse widththe pulse generator can thus cause quite a large linewidth change which is not cautemperature or strain change, and thus can lead to strain and temperature measurerors. As well, the fibers need to be calibrated at every pulse width which may concebe used in the sensor fiber.

All fibers were measured for their strain-linewidth coefficients and their temperalinewidth coefficients. The coefficient was obtained from the slope of the linewidt


idth

erature

idealFig. 7,better

depen-O fiberell forrs havepond towouldmprove

Table 5Strain linewidth coefficients

Fiber Peak 1, Peak 2, Peak 3,strain-linewidth strain-linewidth strain-linewidthcoefficient (MHz/◦C) coefficient (MHz/◦C) coefficient (MHz/◦C)

Corning SMF28 0.0003± 0.0004AllWave −0.0015± 0.0003 −0.0011± 0.0007Depressed Cladding −0.0021± 0.0008ClearLite 1310 −0.0030± 0.0006 n/aa

TruePhase 1310 −0.0045± 0.0017UltraWave IDF 0.0051± 0.0013 0.0117± 0.0054UltraWave SLA −0.0004± 0.0007TrueWave RS 0.0051± 0.0012 0.0082± 0.0024TrueWave XL −0.0005± 0.0007 −0.0049± 0.0040 −0.0018± 0.0011INO GeO2 doped 0.0021± 0.0002

a Shorter pulse width required obscures this peak.

Table 6Temperature linewidth coefficients

Fiber Peak 1, Peak 2, Peak 3,temperature-linewidth temperature-linewidth temperature-linewcoefficient (MHz/◦C) coefficient (MHz/◦C) coefficient (MHz/◦C)

Corning SMF28 −0.3924± 0.0632AllWave −0.4496± 0.1473 −0.7922± 0.6927Depressed Cladding −0.5979± 0.3435ClearLite 1310 −0.4435± 0.1097 0.9621± 0.2781TruePhase 1310 −1.2758± 0.3652UltraWave IDF −0.8563± 0.3541 −5.405± 1.918UltraWave SLA −1.1960± 0.3289TrueWave RS −0.7898± 0.0751 −1.1731± 0.4308TrueWave XL −0.5667± 0.3148 0.0615± 1.0179 −1.0806± 0.8174INO GeO2 doped −0.6978± 0.3476

applied strain or temperature plot. Tables 5 and 6 show the fiber strain and templinewidth coefficients, again with standard error.

A few examples are in order to show the linewidth behavior of more and lessfibers which could be used for linewidth-based strain or temperature separation. Inthe TrueWave XL showed no noticeable linewidth strain dependence, but did showtemperature dependence, and would not be ideal for use to measure strain.

The TrueWave RS shows the strongest overall linewidth strain and temperaturedence, as evidenced by the relatively small standard errors in Tables 5 and 6. The INshowed the strongest strain-linewidth dependence (see Fig. 8), and should work wmeasuring strain, but also has poor temperature linewidth dependence. Some fibea negative coefficient and some a positive one. The smallest standard errors corresbetter strain or temperature-linewidth characteristics—i.e., these calibration curvesgive the smallest temperature or strain measurement errors. One should be able to i


meter

s to aea-ewidth

Fig. 7. Linewidth vs strain and temperature change for TrueWave XL main peak.

Fig. 8. Linewidth vs strain and temperature change for INO GeO2 doped fiber.

the accuracy of a Brillouin sensor system which uses the Brillouin linewidth as a paraby choosing a fiber with good strain/temperature linewidth characteristics.

The slope of the strain-linewidth line in Fig. 8 is 0.0021± 0.0002 MHz/µε. From thisnumber one sees that an error in measuring the linewidth of 1 MHz correspondstrain measurement error of 476 µε. This is an unacceptable error for practical strain msurement systems. This shows that one must be extremely careful when using linmeasurements for strain/temperature separation.


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7. Brillouin power

It was noted as Brillouin spectra were being recorded for each fiber that some fibea much stronger Brillouin loss signal than others. This is as expected since somefibers have such a small MFD. For a Brillouin loss system, the Brillouin spectrum cexpressed as [22]

P(v) = PCWe−αL

(1− exp

(gBPp

Leff

Aeff

)), (5)

wherePCW is the CW laser probe power,α is the linear fiber attenuation coefficient,L isthe fiber length,Pp is the pump pulse power,Leff is the effective length of the fiber, anAeff is the effective area of the fiber. It is noted that asAeff (correspondingly, the MFDgets smaller, the powerP(v) gets larger.

The Brillouin power, in arbitrary units, is recorded for each fiber in Table 7. It is shin comparison to the peak power of the SMF28 lead fiber. It is shown in this masince test parameters, like pulse width or laser power, may have changed slightlmeasurement to measurement—each fiber was tested separately over a 2 weekAlso, splice losses were higher for fibers with non-standard MFDs. Thus each fibebe compared to the SMF28 lead fiber maximum Brillouin power. The power changerelative to SMF28 was calculated by using Power (fiber under test)/power (SMF28).

Fiber attenuation can be neglected since the total fiber lengths—consisting of thunder test and lead fibers—was under 170 m. The measurements were made at roperature and zero strain, with a pulse width of 16 ns. Since the Brillouin power vsomewhat along the fiber length (probably due to polarization issues, even though potion averaging was used), the maximum Brillouin power of each fiber section was recUltraWave SLA fiber has the largest MFD and the smallest relative power ratio. Fwhich showed stronger Brillouin loss signal than the SMF28 lead fiber include Clea1310, UltraWave IDF, TrueWave RS, TrueWave XL, and INO GeO2 doped fibers. TheINO doped fiber likely has the smallest MFD (its core radius is 3.6 µm) and has the lpower ratio. The increase in Brillouin power should allow one to use longer sensorthan would be possible with standard SMF28 since the signal-to-noise ratio is imp

Table 7Brillouin power for each fiber relative to adjacent SMF28

Fiber Power ratio—relative to SMF28

Peak Brillouin power,fiber under test (au)

Peak Brillouin poweSMF28 (au)

AllWave 0.898 38,116 42,466Depressed Cladding 0.904 35,025 38,765ClearLite 1310 1.42 26,396 18,558TruePhase 1310 0.798 19,986 25,047UltraWave IDF 1.40 52,447 37,315UltraWave SLA 0.682 16,479 24,169TrueWave RS 1.59 38,067 23,970TrueWave XL 2.07 31,445 15,207INO GeO2 doped 2.20 27,058 12,293


smallmaylannedristics

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ssibletive byelpeficialbut

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eringations,

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by their use. However, further characterization must be undertaken with some of theMFD fibers: for example, the UltraWave IDF is a negative dispersion fiber, whichadversely effect the pulse characteristics for long sensor fibers. More research is ptoward characterizing these small MFD fibers with non-standard dispersion charactefor long sensing lengths.

8. Conclusion

This paper gives the results of an extensive round of testing for the characteriof optical fibers for Brillouin sensing systems. Measured double and triple peak Brilspectra were shown for several fibers, and temperature and strain coefficient werefor all spectral peaks for all fibers. Measured data leads to the conclusion that it is poto design Brillouin sensor fibers to be more or less strain and temperature sensitailoring the Brillouin frequency of the fiber. It was found that using the linewidth to hseparate strain and temperature may work well for some fiber types but is not benwith others. Using small MFD fibers improved the SNR of the Brillouin loss signal,need to be further tested for use in long sensor systems if their dispersion charactare non-standard. The Brillouin frequency of the fibers tested were found to increasincreasing core radius.

Acknowledgments

The authors wish to thank OFS for providing the OFS optical fiber for testinespecially Paul Neveux, Tom Davis, Ray Kelly, and Cindie Sink. We would also likthank the National Science and Engineering Research Council of Canada, the CaFoundation for Innovation, the New Brunswick Innovation Foundation, and Aliant forporting this research.

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Kellie Brown was born in New Brunswick, Canada, in 1973. She received the BSc degapplied physics in 2000, the MSc degree in physics in 2001, both from the University ofBrunswick, and is currently a PhD student in electrical engineering, also at the University oBrunswick. Her BSc and MSc research focused on the characterization of optical fibers fortion dosimetry and high-data-rate telecommunication systems, respectively. Optimization offibers for Brillouin sensing systems is one of the research areas contributing to her PhD thesi

Anthony W. Brown was born in New Brunswick, Canada, in 1973. He received the BSc degphysics in 1995 and the PhD degree in physics in 2001, both from the University of New Brun


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1983,nadalemen-pmenttennas,on. Re-ng, MRI

His BSc and PhD research focused on the development and optimization of a Brillouin-scabased fiber optic sensor. He is currently employed in the Electrical Engineering DepartmenUniversity of New Brunswick. Current research interests include fiber optic sensing, optical conications, and nonlinear optics.

Bruce G. Colpitts received the BScE, MScE, and PhD degrees in electrical engineering in1985, and 1988, respectively, from the University of New Brunswick, Fredericton, NB, Cawhere he is currently Professor. During his most recent sabbatical leave he coordinated imptation of the Optical Fibre Systems Laboratory which has goals in fibre optic sensor develoand communications. His research interests are primarily related to microwave circuits, anand propagation; including measurement, simulation, hardware development, and applicaticent research projects include harmonic radar design, optical strain and temperature sensiinvestigations, and numerous antenna designs.

characterization of optical fibers for optimization of a brillouin scattering based fiber optic...

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